1. Technical Field
The present invention generally relates to a drive power transmission system for transmitting a drive power to a roller such as a paper feed roller from a drive source such as a motor, and more particularly to a drive power transmission system that has a gear mechanism for connecting a paper feed roller with a paper separation roller such that these rollers cooperate to advance stacked paper one sheet at a time from the top of the stack of paper. The drive power transmission system of the invention is applicable to a document or recording paper supply system on an image recording device such as a copier, a facsimile device, a so-called composite device provided with both copy and facsimile functions, a printer or the like.
2. Background Art
On a conventional document or recording paper supply system on an image recording device as described above, the provision of a roller system for transporting the uppermost sheet of a stack of paper one sheet at a time is known. This roller system includes a gear mechanism that links a feed roller adapted to press and rotate onto the uppermost surface of the stacked paper from above so as to move the uppermost sheet downstream upon its rotation with a separation roller located downstream of the feed roller and adapted to further transport the paper downstream. In the conventional system, the feed roller rotates in synchronization with the downstream separation roller.
However, even after the supply of paper has been exhausted, the feed roller still rotates pressing the empty paper tray due to the synchronization with the downstream separation roller. Therefore, a large load is exerted on the feed roller and in turn to the separation roller downstream of the feed roller and it thus causes breakage of the gear mechanism connecting these rollers.